@-webkit-keyframes animate-cloud {
    from {
        background-position: 600px 100%;
    }
    to {
        background-position: 0 100%;
    }
}
@-moz-keyframes animate-cloud {
    from {
        background-position: 600px 100%;
    }
    to {
        background-position: 0 100%;
    }
}
@-ms-keyframes animate-cloud {
    from {
        background-position: 600px 100%;
    }
    to {
        background-position: 0 100%;
    }
}
@-o-keyframes animate-cloud {
    from {
        background-position: 600px 100%;
    }
    to {
        background-position: 0 100%;
    }
}

html{
    height: 100%;
}
body{
    background:url(cloud.jpg) 0 bottom repeat-x  #049ec4;
    -webkit-animation: animate-cloud 20s linear infinite;
    -moz-animation: animate-cloud 20s linear infinite;
    -ms-animation: animate-cloud 20s linear infinite;
    -o-animation: animate-cloud 20s linear infinite;
    animation: animate-cloud 20s linear infinite;
    width: 100%;
    height: auto;
}